I wanted to finally be able to use the keyboard of newer machines like an eMachines M6805 laptop with AMD64 3000+ x64 CPU from before 2007, wondering if it's USB, but many are still PS/2.

https://www.win.tue.nl/~aeb/linux/kbd/scancodes-11.html#kccd1
KBC command 0xD1 with value 0xFF (write output port and enable all) locks up some machines and it's not vital as it's used for resetting, enabling A20 and enabling keyboard/mouse clocks, but those things can be done in other ways.

Command 0xAE (enable keyboard) as used by VisOpSys (src/kernel/KernelPs2KeyboardDriver.c where it says outPort64(0xAE);) is not normally needed, at least for initialization.